As with the FASTA format, each record starts with a line beginning with ">"
character. There is then a two letter sequence type (P1, F1, DL, DC, RL,
RC, or XX), a semi colon, and the identification code. The second like is
free text description. The remaining lines contain the sequence itself,
terminating in an asterisk. Space separated blocks of ten letters as shown
above are typical.

PirIterator(handle)

handle - input file
alphabet - optional alphabet
title2ids - A function that, when given the title of the FASTA
file (without the beginning >), will return the id, name and
description (in that order) for the record as a tuple of strings.

If this is not given, then the entire title line will be used
as the description, and the first word as the id and name.

Note that use of title2ids matches that of Bio.Fasta.SequenceParser
but the defaults are slightly different.